Dynamic widgets like Tooltip and Select sometimes fail to render some characters #5655
Description
The Bug
When using some utf-8 characters like japanese 「ひらがなカタカナ漢字」 the rendering in certain widgets seems to break non-deterministically. That is for example for tooltips and the select widget, some characters will not be rendered some of the time. For tooltips for example hovering away and back to the widget with tooltip can fix the issue or cause other glyphs to fail to render.
Render failure is as follows, imagine we want to render the string "ひらがなカタカナ漢字" then sometimes this will be displayed as "ひらが カタカナ漢字", or "ひらが カタカナ 字" or "ひらがなカ カナ漢字" or something like that. In essence the width of the string is retained, but some characters seem to be rendered as whitespace (they will have the background color).
I tried the following (none of these have helped):
- overriding the width calculation for the characters
- increase available space for the tooltips
- interleaving 0 space characters between the actual characters
- normalization via unicodedata.normalize
- wrapping the string in rich.text.Text
- wrapping the string in rich.pretty.Pretty
Reproduction
The tooltips in the following app will have this issue. Note however that this is only sometimes so repeated hovering over several tooltips will be necessary to show the issue. I estimate it occurs on 5-10% of attempts.
from textual import app
from textual import widgets
from textual import containers
class MyApp(app.App):
CSS = """
Label {
background: $panel;
padding: 1;
}
"""
def compose(self):
# Create a label that, when hovered, shows our "tooltip".
labels = []
for i in range(10):
label = widgets.Label("Hover over me!", id=f"label-{i}").with_tooltip(f"{i}ヶ月間の平均")
labels.append(label)
yield containers.VerticalGroup(*labels)
if __name__ == "__main__":
app = MyApp()
app.run()Textual Diagnostics
textual diagnose
Versions
| Name | Value |
|---|---|
| Textual | 2.1.2 |
| Rich | 13.9.4 |
Python
| Name | Value |
|---|---|
| Version | 3.13.2 |
| Implementation | CPython |
| Compiler | GCC 11.4.0 |
| Executable | /home/kourion/git/textual-bug/venv/bin/python3.13 |
Operating System
| Name | Value |
|---|---|
| System | Linux |
| Release | 5.15.167.4-microsoft-standard-WSL2 |
| Version | #1 SMP Tue Nov 5 00:21:55 UTC 2024 |
I confirmed the same bug on windows 11 powershell and windows 10 powershell.
Terminal
| Name | Value |
|---|---|
| Terminal Application | Windows Terminal |
| TERM | xterm-256color |
| COLORTERM | Not set |
| FORCE_COLOR | Not set |
| NO_COLOR | Not set |
Rich Console options
| Name | Value |
|---|---|
| size | width=124, height=38 |
| legacy_windows | False |
| min_width | 1 |
| max_width | 124 |
| is_terminal | True |
| encoding | utf-8 |
| max_height | 38 |
| justify | None |
| overflow | None |
| no_wrap | False |
| highlight | None |
| markup | None |
| height | None |
Video
Here you can see that the string "4ヶ月間の平均" gets rendered as "4ヶ月間の 均"